1. Step
Heat oil in a large pot or Dutch oven over medium heat. Add leek; cook, stirring often, until very tender, about 10 minutes. Add onion, carrots, celery and parsnips; cook, stirring occasionally, until the vegetables are slightly tender, 6 to 8 minutes. Stir in garlic, oregano, salt and pepper; cook, undisturbed, until fragrant, about 1 minute. Add kale; cook, stirring often, until it's just starting to wilt, about 2 minutes. Pour in broth; bring to a boil over medium heat. Cover, reduce heat to medium-low and simmer, stirring occasionally, until the kale is tender, about 20 minutes.